1. Field of the Invention
This invention relates to new solutions or dispersions of acylurea group-containing anionically-and optionally nonionically hydrophilically-modified polyisocyanate addition products, to a process for the production thereof and to the use thereof as coating agents for flexible or inflexible substrates or as sizing agents for paper.
2. Description of the Prior Art
Processes for the production of ionically-modified polyurethanes are known and are described, for example, in the following literature: DE-PS No. 880,485, DE-AS No. 1,044,404, U.S. Pat. No. 3,036,998, DE-PS Nos. 1,178,586, 1,184,946, DE-AS Nos. 1,237,306, 1,495,745, DE-OS Nos. 1,595,602, 1,770,068, 2,019,324, 2,035,732, 2,446,440, 2,345,256, 2,345,245, 2,427,274, U.S. Pat. No. 3,479,310 and Angewandte Chemie 82, 53 (1970) and Angew. Makromol. Chem. 26, 85 et seq (1972).
Aqueous dispersions of the aforementioned polyurethanes may be used in a wide range of applications, for example as adhesives or for coating different flexible or inflexible substrates.
In spite of the plurality of known processes and the products obtained thereby, there still remains a need for aqueous dispersions having specific properties.
There is provided by the process described in more detail below the opportunity of specifically modifying, within a wide range, the property spectrum of such products in a straightforward manner by selecting an organic substituent which is bound via an acylurea group.
The production of acylurea group-containing isocyanate polyaddition products is known and described, for example, in DE-OS No. 2,436,740 or DE-OS No. 2,714,293. According to these known processes, the products are either produced in solution and then converted with film formation to coatings, lacquer coatings or films (DE-OS No. 2,436,740) or acylurea group-containing polyhydroxyl compounds are first produced, which may then be converted to acylurea group-containing foams (DE-OS No. 2,714,293). Nonetheless, it was not foreseeable that this principle is transferable to the chemistry of aqueous polyurethane dispersions, more particularly that the dispersions of polyurethanes according to the present invention, which are described in more detail below, having hydrophobic side chains bound via acylurea groups, would be at least equal to, for example, DE-OS No. 2,400,490 in terms of suitability as sizing agents for paper. The dispersions or solutions of carboxylate group- and hydrophobic side chain-containing polyurethanes in particular, which are described in more detail below, are superior to the paper sizing agents disclosed in the latter-mentioned prepublications because of the reduced tendency thereof to form foam in the liquor and in terms of the suitability thereof both for alum-free and alum-containing or pre-sized or wood-containing paper.